1. Field of the Invention
Embodiment relates to a halftone mask, and more particularly, to a halftone mask that can uniformly form the heights of underlying layers in two regions spaced from each other, a manufacturing method thereof and a method for forming a film using the same.
2. Discussion of Related Art
An organic light emitting display device has advantages in view of rapid response speed as well as wide view angle and excellent contrast so that it has been spotlighted as a next generation flat panel display device.
In manufacturing the organic light emitting display device, the integration of a panel and a driving circuit is very important for the lightweight and slimness and the reduction in production costs of the panel. For example, with a manufacturing process using a low temperature poly silicon (LTPS) technology, the number of masks is reduced, making it possible to enhance the productivity of the device and to seek for the cost reduction thereof.
One of the methods to reduce the number of masks is to use a halftone mask. If the halftone mask is used, pixel defining layers that cover a pixel electrode to expose some regions of the pixel electrode of the organic light emitting display device can be patterned using one mask.
However, when the pixel defining layers are patterned using one mask, a height difference is generated between the regions of the pixel defining layers on left and right sides of the exposed pixel electrode so that it may cause a defect in a subsequent process.
For example, the height difference between the regions of the pixel defining layers on both sides of the pixel electrode may cause a defect in an organic deposition such as a light emission layer, etc. or in a metal deposition such as an electrode layer, etc. Further, the pixel defining layer also functions as a spacer when masks for depositing the organic material or the electrode, etc. are attached but in that case, the masks get loose in some regions so it may cause a defect in deposition.